When a semiconductor device on a mount board consumes a large amount of power, the semiconductor device has to be cooled within an operating temperature range using, for example, a heat sink for cooling to secure the operation of the semiconductor device. In one method, a heat sink is mounted using a spring-like retaining member. When a heat sink is mounted on a semiconductor device using a spring-like retaining member, in order to ensure the cooling performance of the heat sink while avoiding placing stress on the semiconductor device, a press-fitting force exerted on the semiconductor device from the heat sink has to be within a certain range.
Semiconductor devices vary in height according to the manufacturer and packaging material. Thus, when semiconductor devices having different heights are mounted on a mount board, several types of spring-like retaining members for fixing heat sinks, or several types of connecting members with which the retaining members are engaged, are used.
FIG. 1 illustrates an example of a heat sink mounted using a spring-like retaining member. In the example in FIG. 1, a spring-like retaining member 20 is fitted to a groove between fins provided on the surface of a heat sink 10, and the heat sink 10 is mounted on a semiconductor device (not illustrated) by means of the elastic force of the spring-like retaining member 20. The ends of the spring-like retaining member 20 can be engaged with connecting members 30 provided on a mount board. FIG. 2 illustrates an example in which a heat sink 11 having pin-like fins is mounted on a semiconductor device (not illustrated) using a spring-like retaining member 21. In this example as well, the spring-like retaining member 21 is fitted to a groove between the pin-like fins, and the ends of the retaining member 21 are engaged with connecting members 31 provided on a mount board, whereby the heat sink 11 is mounted on the semiconductor device by means of the elastic force of the spring-like retaining member 21.
As illustrated in FIGS. 1 and 2, when the heat sinks 10 or 11 are mounted on semiconductor devices having different heights using the spring-like retaining members 20 or 21, in order to mount the heat sinks on the semiconductor devices with a uniform press-fitting force, it is necessary to change the angle of both wings having sections for engaging the ends of the retaining members 20 or 21 or to change the heights of the connecting members 30 or 31.
FIG. 3 illustrates an example in which the same kind of heat sinks 10 are mounted on semiconductor devices 40 and 41 having different heights on a mount board 50, using retaining members 20 and 22 having different heights. In FIG. 3, the connecting members 30 having the same heights are used. To mount the heat sink 10 on the semiconductor device 41 having a tall height, the retaining member 22 having a tall height is used. To mount the heat sink 10 on the semiconductor device 40 having a short height, the retaining member 20 having a short height is used.
FIG. 4 illustrates an example in which the same heat sinks 10 are mounted on the semiconductor devices 40 and 41 having different heights on the mount board 50, using connecting members 30 and 32 having different heights. In FIG. 4, the same retaining members 20 are used. To mount the heat sink 10 on the semiconductor device 41 having a tall height, the connecting members 32 having a tall height are used. To mount the heat sink 10 on the semiconductor device 40 having a short height, the connecting members 30 having a short height are used.
Japanese Laid-open Patent Publication Nos. 11-150220 and 2005-150192 disclose methods for mounting a heat sink. However, in either case, when heat sinks are mounted on semiconductor devices having different heights, the height of retaining members or the height of connecting members has to be changed.
As described above, when heat sinks have grooves that receive the retaining member at the same height, in order to mount the same heat sinks on semiconductor devices having different heights, various types of retaining members or connecting members corresponding to the number of heights of the semiconductor devices are needed. The use of various types of retaining members or connecting members may lead to an incorrect choice of components, resulting in a mounting error. A mounting error may cause excessive pressure to be applied to components, damaging the components, or it may result in insufficient press-fitting force, causing cooling failure.
Thus, the present application addresses enabling the same heat sinks to be mounted on the semiconductor devices using the same retaining members and the same connecting members, and with the same press-fitting force when assembling a mount board on which semiconductor devices having different heights and requiring heat sinks are mounted.